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Ionic 3 – HTTP Requests – Retrieving a Photo from a Google Place

As I become more comfortable with Ionic 3 and its functionality, I wanted to share how to connect to the Google Maps API, retrieve a specific place and then to request a photo from that requested place.

In doing so, you will then know how define a HTTP object using TypeScript and using ES6 Promises in order to make a callback function that requests the photo using that HTTP object.

This functionality stems from an app that I made called CoffeeTrail.

CoffeeTrail

It’ll be on the iOS store very soon but be sure to check it out on Android here.

Setup Project

As always we can generate our Ionic 3 project using the command

ionic start ionic2-nearby blank --v2

We then want to generate our locations provider.

ionic g provider Locations

This is a provider that contains all our methods that we will use to request data from Google’s APIs. When you open up this locations provider you will see that the Ionic CLI has automatically injected a HTTP object into the constructor for us.

We utilize a ES6 JavaScript Promise that will use the http object created in our constructor in order to make the request along with the details of the location which you can change for your own personal preferences.

You will of course have to reference the API key that you created earlier on in the apiKey variable of type string..

This Promise will return true or resolve when the the request has been completed and the data has been returned. The results of the data is mapped to a new json object which we assign to the this.data variable through ES6’s arrow functions .

This data will be resolved/returned when we call it in our location-details file.

This will take in a photo reference string as a parameter in order to a retrieve a specific photo based on the location from the locations/location returned from our getLocation method.
So how do we get the photo reference from the data set returned from getLocation? Well we can do this in the locations-list file.

Display Photo

Our location-details.html file should look like this to display the retrieved image of the location.

Location Details

No image available for location.

Notice how we use the async pipe with the current image template variable.

This is because some asynchronous data objects can be a bit tricky to display without async pipe. The data source is an Observable that contains an array so using the async pipe secures it so to speak.

We then use the ng-template (which is new to Angular 4) syntax to display error text if no image can be retrieved.

No image available for location.

So in our location.details.ts file we need to use our getLocation method in order to get a place and then to send a photo reference from that place to the getPhoto method.

This is just one way to retrieve data from an API in an Ionic application. The use of Angular 4 in an Ionic 3 project enables a developer to makes a request for some data and then to easily share that data throughout the rest of the components using a service or in this case, using our location.ts.provider.